This Program Project, entitled "Immunoglobulin Variable Region Genes and Proteins" is a multi-disciplinary research effort focused on the goal of understanding the genetics, expression, and function of variable region genes and proteins in man and in an avian species. Major emphasis is on how somatic mutation plays a role in the generation of antibody diversity. The unifying theme of the individual projects is the analysis of immunoglobulin variable regions. In some instances the studies are on deliberately produced hybridomas, in others, in spontaneous transformations which occur during human malignancies such as chronic lymphatic leukemia and acute lymphatic leukemia. Five projects are proposed, bringing together five independent investigators around three core components. One core laboratory (Core A) is a shared resource that will provide cell culture facilities for all members of the Program Project. Core B will provide molecular biology expertise for all members of the Program Project.